Multi-level BOMs can be uploaded using a “Parent Part Number” column and the correlation of that data creating a “Parent/Child” relationship with the “Customer Part Number” column.
When uploading your BOM, you will check the box for Is this a Multi-Level BOM? in order to use Parent Part Numbers. This opens up the column for you to map that Parent Part Number.
When mapping the Parent Part Number column, you will then only be able to map one quantity. Instead, you can choose to use Multipliers as needed.
Once your BOM is loaded, you will see a Parent PN and Level columns to display your multi-level BOM.
You can review the article BOM Upload for more information in general about uploading BOMs.